We investigate new polyaniline copolymers with flexible aliphatic side chains as a compatibilizer. Each polyaniline compatibilizers bearing small number of aliphatic side chain ; ethylhexyl (PA 2,6), hexyldecyl (PA 6,10), hexadecyl (PA 16) groups can increase the interfacial interaction between MWCNT and polyethylene (PE) matrix, also prevent dramatic reduction of its electrical conductivity. In absent of compatibilizer, the aggregation of MWCNT is observed in PE/MWCNT composite. The PA 6,10/MWCNT is well dispersed in PE matrix and excellent film forming ability. In contrast, PA 2,6/MWCNT and PA 16/MWCNT showed relatively poor dispersion in PE matrix which cause phase separation of composite film. As a result, PA6,10/MWCNT/PE exhibits lowest electrical resistance, which is significantly lower than PA 2,6/MWCNT/PE and PA16/MWCNT/PE.